Seminars Archive

Precision laboratory astrophysics in the EUV and soft X-ray region with synchrotron radiation and free-electron lasers

Abstract
We propose the use at Elettra and Fermi of a miniature electron beam ion trap (EBIT) of Polar-X type [1] as a transparent target of highly charged ions (HCI) for the X-ray photon beam, which pass the EBIT and reach other experiments downstream for simultaneous photon energy as well as pulse intensity calibration. With this setup, HCI can be prepared, stored and cooled, and their fluorescence spectrum compared with, e. g., the absorption spectrum of molecules and atoms with much better photon energy determination than presently achievable. This will allow to exploit the high-resolution monochromators in the soft x-ray region, and improve our earlier work at FLASH (50 eV)[2] and LCLS (800 eV) [3], as well as at synchrotron-radiation facilities BESSY and PETRAIII on photoionization [4-6] and X-ray resonant fluorescence spectroscopy [7-8]. Upcoming space observatories (XRISM, Athena) with high-resolution X-ray microcalorimeters will benefit from the accurate laboratory atomic data obtained with this method. By achieving accuracies in the sub-meV level, it will also enable far more stringent tests of advanced theoretical electronic structure calculations than previous experiments. Furthermore, besides of resolving the natural linewidth of E1 transitions at high resolution, the precise timing of FEL pulses enables pump-probe experiments and transition-probability determinations, an interesting possibility also in combination with coherent, seeded FEL pulses addressing long-lived, elec- tron-density dependent metastable states.
References
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[2] S. W. Epp et al., Phys. Rev. Lett. 98, 83001(2007)
[3] S. Bernitt et al., Nature 492, 225 (2012)
[4] M. C. Simon et al., Phys. Rev. Lett. 105, 183001 (2010)
[5] M. C. Simon et al., J. Phys. B: At. Mol. Opt. Phys. 43, 065003 (2010)
[6] R. Steinbrügge et al., Phys. Rev. A 91, 032502 (2015)
[7] J. K. Rudolph et al., Phys. Rev. Lett. 111, 103002 (2013)
[8] S. W. Epp et al., Phys. Rev. A 92, 020502(R) (2015)